The present disclosure generally relates to the field of motor vehicle braking systems. More precisely, a sensor module for use with a master cylinder of a braking system is described.
Underpressure brake boosters are used in motor vehicles in order to amplify the foot force applied by the driver to a brake pedal. A conventional underpressure brake booster has an underpressure chamber and an operating chamber which are separated from each other by a piston which is in the form of a diaphragm. The diaphragm is in turn connected in a power-transmitting manner to an input-side activation element of a master cylinder on which the foot force applied by the driver also acts.
During the driving operation, an underpressure is constantly maintained in the underpressure chamber whilst the operating chamber may selectively be connected to the underpressure chamber or to atmospheric pressure. If the two chambers are connected to each other, the same pressure is present in the two chambers and the diaphragm is located in its initial position. In the context of a braking operation, the operating chamber is fluidically separated from the underpressure chamber and the operating chamber is further connected to atmospheric pressure. The resultant pressure increase in the operating chamber results in a pressure difference at the diaphragm. That pressure difference in turn brings about a displacement of the diaphragm in the direction of the underpressure chamber and therefore an amplification force at the activation element of the master cylinder.
In order to assess the performance of an underpressure brake booster, it is desirable to monitor the pressure in the underpressure chamber with sensors. In previous monitoring solutions, an underpressure sensor is fitted to the brake booster in order to establish the air pressure. If the brake booster fails and has to be changed, however, this requires that the costly underpressure sensor also be replaced. As an alternative to this, the underpressure sensor may be disassembled from the defective brake booster and mounted on the new brake booster, but this involves great expenditure of time.
In order to avoid these disadvantages, it is proposed in DE 10 2004 013 191 A to provide an underpressure region which communicates with the underpressure chamber of the brake booster in the master cylinder and to arrange the underpressure sensor in that underpressure region of the master cylinder. A particular construction makes provision for the underpressure sensor having a position sensor of a brake light switch to be integrated in a sensor module and for the entire sensor module to be provided in the underpressure region of the master cylinder. The sensor module comprises a finger-like carrier member, at the tip of which the underpressure sensor and the position sensor are received. In order to position the sensors in the underpressure region of the master cylinder, the carrier with the sensors received at the front side is directed through a channel which is formed in the master cylinder and which opens in the underpressure region.